Blister packs are of course well known for the storage and dispensing of pills, tablets and capsules, which are stored individually in cavities in a multi-cavity tray and removed by pushing each pill, tablet or capsule through a rupturable film or foil covering the cavities. The film or foil cover may be paper or a plastics film that can be peeled or torn away to expose the medication in the tray cavities, but is generally aluminium foil, which has the dual advantage of being easily rupturable and vapour-impermeable. Such blister packs normally carry only one unit dose of the same medication in each cavity.
Mixed medication blister packs have been proposed, having larger cavities for filling by a pharmacist, wherein each cavity in a multi-cavity tray can be filled with a mixture of medications. Typically, a tray may have a 2×7, 3×7, 4×7 or 5×7 array of cavities corresponding to 2, 3, 4 or 5 predefined medication times per day over a 7-day period, or one dose prescribed per day over a 2, 3, 4 or 5 week period. For example, a 4×7 tray may be filled with the medication to be taken at breakfast-time, lunchtime, early evening and immediately before retiring each day for a week, and then the filled cavities sealed with a rupturable or sequentially rupturable film or foil cover. Printed instructions on the pack identify the intended sequence of opening the individual cavities to dispense their contents according to the prescribed dosage regimen.
Disadvantages of conventional blister packs using a rupturable cover film are the difficulty experienced by some patients, particularly the elderly, in pushing the medication through the cover film, the need for expensive laminating equipment to seal the aluminium cover film over the cavities after the initial filling, and the difficulty experienced by the user in selecting the cavity containing the medication to be dispensed if the medication is pushed up through the foil from below. If the wrong cavity is opened by mistake then re-sealing is impossible because the cover film has ruptured.
A major disadvantage of the blister pack using a peelable cover film is the difficulty experienced by the user in peeling or tearing away a single selected portion of the cover film to expose the contents of only one preselected cavity. This can be achieved by scraping a finger-nail over a corner or tab portion of a segment of the cover film sealing the preselected cavity, but grasping that corner to peel away the complete segment sometimes requires considerable manual dexterity and possibly good eyesight, which is beyond the abilities of many elderly users. Also, if a tacky peelable adhesive is used to adhere the cover film to the tray, it is desirable to prevent the contents of the tray from coming into contact with the adhesive. Finally, the film cover film may not have as high a vapour impermeability as metal foil, so there is a reluctance on the part of pharmacists to pre-fill a mixed medication blister pack with medication for administration more than seven days in advance of the filling date, lest the medication deteriorates due to storage in humid ambient conditions.
WO 2005/023670 to the present Applicant describes a container that aims to overcome some or all of the above problems and disadvantages. The container is for storing and dispensing medication and includes a tray having a generally planar top surface into which has been formed one or more discrete cavities for receiving the medication. A cover film is adhered to the generally planar top surface of the tray by a layer of peelable adhesive to seal the one or more cavities to retain the medication in the one or more cavities. The cover film has pre-formed tear lines defining a tear-off portion per cavity to retain the medication in that cavity until it is removed by tearing along its tear lines. In practice it will be readily appreciated that the or each tear-off portion can also be defined by cut lines extending completely through the material of the cover film. The or each tear-off portion of the cover film has low vapour transmission properties in the area which in use overlies the associated cavity, those low vapour transmission properties being created by a barrier patch with high vapour barrier properties shaped and sized to overlie the associated cavity. The or each barrier patch is adhered to the underside of the cover film by the same layer of peelable adhesive as that which adheres the cover film to the top surface of the tray.
The barrier patch beneath the or each tear-off portion can be created from a single sheet of barrier film as follows. A single sheet of barrier film is secured to the underside of the cover film by a peelable adhesive. The barrier film has pre-formed tear-lines defining the periphery of the or each vapour-resistant barrier patch so that peeling away the majority of the barrier film from the cover film immediately prior to application of the cover film to secure it to the generally planar top surface of the tray exposes the peelable adhesive in areas necessary for adhesion to the tray but leaves a barrier patch attached to the underside of the or each tear-off portion of the cover film. In practice it will be readily appreciated that the or each barrier patch can also be defined by cut lines extending completely through the material of the barrier film.
The sheet of barrier film can have a further pre-defined tear line (or cut line) close to one edge thereof to define a tear-off strip which when removed exposes a location anchorage area of the peelable adhesive on the underside of the cover film, for adhering an edge portion of the cover film to an edge portion of the tray before peeling away the majority of the barrier film and adhering it over the cavities. To assist in the process of adhering the cover film to the top surface of the tray, the tray can have upstanding cover film location means. The cover film can have cooperating means for accurate location of the cover film over the tray with the one or more cavities and associated tear-off portions in register before adhering the cover film to the tray.
EP 1357050 to the present Applicant discloses an alternative container where the tear-off portions of the cover film have an associated lug portion that is not secured to the tray in use, for gripping by a user preparatory to tearing off the tear-off portion. The generally planar top surface of the tray also has an upwardly extending protrusion positioned to be located beneath each lug portion in use to bend that lug portion upwardly out of the plane of the remainder of the cover film when the cover film is secured to the tray. Because the or each lug portion is bent up out of the plane of the remainder of the cover film when the film is applied, it can very easily be grasped by the user for removal of the tear-off portion. This makes the container particularly suitable for elderly users or those with limited manual dexterity.
Although the containers described in WO 2005/023670 and EP 1357050 are considered to be easier to use than blister packs having rupturable or peelable cover films, there is still a potential problem that the medication can be incorrectly dispensed from the containers. It is known to apply electrically conductive tracks on to a rupturable cover film to provide a notification when the contents of a particular cavity are dispensed. However, such a system has not been applied to containers where the cover film has tear-off or removable portions.